Automatically generated captions can accelerate production, but a synchronized transcript is not accessible simply because it exists.
Captions carry more than words
Under W3C’s WCAG 2.2 success criterion 1.2.2, captions for prerecorded synchronized media convey speech and meaningful non-speech audio such as speaker changes and relevant sounds, within the criterion’s specified exceptions. A transcript alone may not be synchronized to the video; subtitles that omit vital sound cues may leave people without equivalent information. This is a technical accessibility reference, not a claim that WCAG 2.2 is automatically binding law worldwide.
Common automatic errors
Speech recognition may substitute names, numerals or technical terms, miss overlapping voices, drop negation, mishandle accents and fail to label who is speaking. Music lyrics, alarms and off-screen sound effects may be absent. The model can also create words during silence or assign speech to the wrong person. Review against the actual final audio, not a draft script that may have changed during editing.
A practical review pass
First compare each caption line with the recording and correct every meaning-changing term. Then inspect timing: lines should appear and disappear when the corresponding audio occurs, with readable segment lengths and sensible breaks. Label speakers when necessary and capture critical sounds. Finally verify punctuation and readability without compressing away meaning. Have a qualified reviewer check languages they actually understand.
Visual accessibility still matters
Do not place captions over crucial on-screen text. Test contrast, font readability, resize behavior and whether a viewer can turn closed captions on or off where supported. Audio description or a suitable media alternative may be needed for visual-only information; captions do not replace that requirement. A fully automated caption workflow needs an accessible correction mechanism.
Example: an educational tutorial
A video says ‘do not restart the machine’ while background noise causes an ASR system to omit ‘not’. The line remains grammatically plausible but reverses the instruction. In a technical or safety-sensitive lesson, that error should block publication until corrected. Source audio and timestamped caption files should be preserved for editorial audit.
Multilingual captions
Translated captions require meaning review, not word-for-word substitution. Terms of art, local names and measurements can shift during translation. Verify line timing after text expansion, right-to-left display when relevant and screen-reader behavior in the actual player. Avoid asserting support for a language without tests of that specific workflow.
Publication check
Keep the corrected caption file, review date, language, media hash, responsible reviewer and outstanding exceptions. W3C guidance is a strong reference for accessibility design, but country-specific legal duties and contractual requirements must be assessed separately.
Sources & Further Reading
- WCAG 2.2 overview — W3C WAI.
- W3C WCAG 2.2 Understanding SC 1.2.2 Captions (Prerecorded) — W3C WAI.
- NIST AI 600-1 Generative AI Profile — NIST.
Primary Scope and applicability vary by task and jurisdiction. This article is educational guidance, not legal, medical or financial advice.